System and method for electrochemical cyclic oxidation of landfill leachate

Abstract

The present invention provides a system and method for pretreating landfill leachate by electrochemical cyclic oxidation, by which organic matter having ultraviolet absorption (UVA 254 ) at 254 nm in the landfill leachate can be effectively removed, so that the treated landfill leachate is used for co-treatment by dilution with municipal sewage. Specifically, the UVA 254 of the landfill leachate is reduced by more than 80% by the system and method, the energy requirement for treating the landfill leachate is less than 20 kWh / m 3 , the energy expenditure is significantly reduced, the residual chlorine of the fully treated landfill leachate is reduced to 25 mg / L or less in terms of Cl2, and the released chlorinated by-products meet the standards and can be safely used.

Description

Technical Field

[0001] This invention relates to the pretreatment of landfill leachate, and particularly to a multi-stage process including electrochemical oxidation and photolysis to remove ultraviolet A (UVA) absorption at 254 nm from landfill leachate. 254 Organic materials, thus used for co-treatment by diluting municipal sewage. Background Technology

[0002] Landfill leachate varies considerably in composition, depending on the age of the landfill and the type of waste it contains. Landfill leachate is primarily generated by rainwater seeping through waste deposited in the landfill. Once it comes into contact with decomposing solid waste, the leachate becomes contaminated, flowing out primarily as solutions and suspensions of various waste products. The decomposition of this carbonaceous material increases the volume of leachate, generating a large amount of other materials, including methane; carbon dioxide; and complex mixtures of organic acids, aldehydes, alcohols, and monosaccharides.

[0003] On-site treatment typically involves treating landfill leachate before it is discharged into the environment. This on-site treatment often employs multi-stage processes, which are both complex and expensive. A common alternative to on-site treatment is co-treatment by diluting the landfill leachate with municipal sewage. As of 2019, approximately 18 million metric tons of landfill leachate in the United States were co-treated into municipal sewer systems. At the Northeast New Territories landfill in Hong Kong, approximately 1000-2000 cubic meters of leachate are discharged daily. 3 The leachate from the landfill is co-treated.

[0004] Although co-treatment is significantly less expensive than on-site treatment, it has been found to be detrimental to downstream wastewater treatment plants. Landfill leachate contains high concentrations of dissolved organic matter (DOM). When discharged into municipal sewer systems, DOM can absorb UV rays during the ultraviolet (UV) disinfection phase at downstream wastewater treatment plants. Because DOM absorbs UV rays, the UV output power must be increased to achieve the same effect on the wastewater. This increases the overall cost of treatment, as well as associated costs such as more frequent replacement of UV lamps. DOM absorption of UV rays also increases the risk to the general population, as there is a possibility of incomplete or inadequate disinfection of the wastewater. Landfill leachate has high UV absorption (UVA) at 254 nm. 254 This will affect the daily emission rate. If UVA 254 Higher UVA levels may reduce the daily discharge rate into the sewage pipeline, leading to leachate accumulation at the treatment site. Therefore, to mitigate these inherent problems in co-treatment, the UVA of landfill leachate must be reduced before co-treatment with wastewater.254 .

[0005] It has been found that approximately 90% of landfill leachate contains UVA. 254 The substances in UVA are small molecules below 1 kDa, which makes traditional treatment methods such as coagulation sedimentation and biological treatment ineffective in reducing UVA. 254 For this reason, it has been found that biological treatment can only reduce UVA by 20-30%. 254 Furthermore, advanced filtration processes, such as nanofiltration and reverse osmosis, require significant amounts of chemicals for membrane cleaning and antifouling, making them costly in terms of both money and time. These technologies also generate a secondary waste called leachate concentrate, which can reach concentrations up to 20 times higher than the original leachate, limiting its application. Leachate concentrate is also disposed of through co-treatment with municipal wastewater. Therefore, regardless of the treatment method, landfill leachate is destined for co-treatment with wastewater. Consequently, it is necessary to adopt economical practices to promote on-site co-treatment of leachate and wastewater.

[0006] Advanced oxidation processes (AOPs) such as Fenton oxidation and electrochemical oxidation have been tested for treating landfill leachate. These processes break down the organic matter in the leachate, thereby reducing UVA. 254 However, the Fenton oxidation process requires expensive hydrogen peroxide activated by a non-regenerative catalyst (such as iron). On the other hand, electrochemical oxidation generates an oxidant in situ by converting chlorides in the leachate. The main product produced is hypochlorite (OCl₂). - ), hydroxyl radicals (OH) · ) and reactive chlorine substances (RCS), which rapidly attack substances resistant to UVA. 254 The organic bonds. Among these three, the order of reactivity is OH... · >RCS>OCl - , but OH · RCS requires toxic or fragile electrode coatings to generate.

[0007] An alternative to the aforementioned electrochemical oxidation technique is to generate OCl using an economical electrode (e.g., a mixed metal oxide). - And apply UV radiation to OCl - Photolysis to OH · And RCS. However, in testing, applying this alternative to landfill leachate required 2-8 hours of treatment, resulting in a wastewater exceeding 260 kWh·m³. -3 Energy expenditure. Electrochemical technology has significant advantages, such as ease of maintenance, no need for chemical additions, and flexibility to be tailored to match desired degradation. Therefore, a system and method for the electrochemical cyclic oxidation of landfill leachate is needed to address the aforementioned issues. Summary of the Invention

[0008] In view of this, the present invention provides a system and method for pretreating landfill leachate by electrochemical cyclic oxidation, which can reduce the UVA content of landfill leachate. 254 And it can significantly reduce energy expenditures.

[0009] According to a first aspect of the present invention, a system for electrochemically circulating oxidation of landfill leachate is provided, wherein the system comprises: a shell divided into a first reaction chamber and a second reaction chamber, wherein the first reaction chamber and the second reaction chamber are in unidirectional communication, and wherein the shell has an inlet and an outlet, the inlet being configured to input landfill leachate to be treated into the first reaction chamber, and the outlet being configured to discharge sufficiently treated landfill leachate from the second reaction chamber; an anode and a cathode, located within the first reaction chamber, configured to electrochemically oxidize the landfill leachate input into the first reaction chamber; at least one first ultraviolet radiation source, located within the first reaction chamber, configured to apply first ultraviolet radiation to the landfill leachate after electrochemical oxidation treatment; and at least one second ultraviolet radiation source, located within the second reaction chamber, configured to apply second ultraviolet radiation to the landfill leachate from the first reaction chamber.

[0010] According to a second aspect of the present invention, a method for electrochemically circulating oxidation of landfill leachate using the system described in the first aspect of the present invention is provided, characterized in that the method comprises the following steps: (1) introducing landfill leachate into a first reaction chamber and electrochemically oxidizing the landfill leachate; (2) subjecting the electrochemically oxidized landfill leachate to first ultraviolet radiation using a first ultraviolet radiation source to generate partially treated landfill leachate; (3) conveying a portion of the partially treated landfill leachate to a second reaction chamber and subjecting it to second ultraviolet radiation using a second ultraviolet radiation source in the second reaction chamber to generate fully treated landfill leachate; and (4) discharging the fully treated landfill leachate from the second reaction chamber.

[0011] This invention provides a system and method for pretreating landfill leachate through electrochemical cyclic oxidation. This system and method can effectively remove ultraviolet A (UVA) molecules with ultraviolet absorption at 254 nm from landfill leachate. 254 The system and method utilize organic matter to treat landfill leachate, thereby enabling its co-treatment through dilution with municipal wastewater. Specifically, the system and method enhance the UVA of the landfill leachate. 254Reduced by more than 80%, bringing the energy requirement for treating landfill leachate below 20 kWh / m³. 3 It significantly reduces energy expenditure, lowers the residual chlorine in fully treated landfill leachate to below 25 mg / L (Cl2), and the released chlorinated byproducts meet the standards and can be used safely. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other implementation schemes can be obtained based on these drawings without creative effort. In the drawings, similar reference numerals consistently denote corresponding components.

[0013] Figure 1 A system for electrochemically circulating oxidation of landfill leachate is schematically illustrated.

[0014] Figure 2 The dot plot shows the use of Figure 1 The method for electrochemical cyclic oxidation of landfill leachate by the system describes the change of UV absorption at 254 nm over time in the landfill leachate during the initial and cyclic phases.

[0015] Figure 3 The point graph is shown in Figure 2 The change of residual chlorine concentration over time in the initial and cyclic phases.

[0016] Figure 4 The bar chart shows the concentration of chlorinated byproducts released after electrochemical cyclic oxidation of landfill leachate. Detailed Implementation

[0017] The present invention will now be clearly and completely described in conjunction with its embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0018] Currently, landfill leachate is mainly treated by diluting it with municipal sewage for co-treatment. However, it has been found that landfill leachate contains high concentrations of dissolved organic matter (DOM). When it enters the sewage treatment plant, it absorbs UV rays during the ultraviolet (UV) disinfection stage of the sewage, which affects the treatment effect of the wastewater and also increases the related components. In addition, the existing treatment methods have a large energy expenditure.

[0019] Therefore, the present invention provides a system and method for pretreating landfill leachate to reduce UVA levels in landfill leachate. 254 And significantly reduce energy expenditures.

[0020] Specifically, according to a first aspect of the present invention, a system for electrochemically circulating oxidation of landfill leachate is provided, wherein the system comprises: a shell divided into a first reaction chamber and a second reaction chamber, wherein the first reaction chamber and the second reaction chamber are in unidirectional communication, and wherein the shell has an inlet and an outlet, the inlet being configured to input landfill leachate to be treated into the first reaction chamber, and the outlet being configured to discharge fully treated landfill leachate from the second reaction chamber; an anode and a cathode, located in the first reaction chamber, configured to electrochemically oxidize the landfill leachate input into the first reaction chamber; at least one first ultraviolet radiation source, located in the first reaction chamber, configured to apply first ultraviolet radiation to the landfill leachate after electrochemical oxidation treatment; and at least one second ultraviolet radiation source, located in the second reaction chamber, configured to apply second ultraviolet radiation to the landfill leachate from the first reaction chamber.

[0021] Figure 1 A system for the electrochemical cyclic oxidation of landfill leachate is schematically illustrated. For example... Figure 1 As shown, a system 10 for electrochemically circulating oxidation of landfill leachate includes a housing 11 divided into a first reaction chamber 12 and a second reaction chamber 14; a cathode 20 and an anode 22; at least one first ultraviolet radiation source 24 and at least one second ultraviolet radiation source 26. The housing 11 has an inlet 16 adapted to introduce landfill leachate (LL) to be treated into the first reaction chamber 12, and also has an outlet 18 for discharging fully treated landfill leachate (FTLL) from the second reaction chamber 14. The cathode 20 and anode 22 are located within the first reaction chamber 12 and connected to a power source (V) for electrochemically oxidizing the landfill leachate in the first reaction chamber 12 to produce hypochlorite (OCl). - At least one first ultraviolet radiation source 24 is located within the first reaction chamber 12 for reacting the landfill leachate and hypochlorite (OCl) after initiating the electrochemical oxidation of the landfill leachate. - The application of first ultraviolet radiation generates hydroxyl radicals (OH). · ) and reactive chlorine substances (RCS). Hypochlorite (OCl) - ), hydroxyl radicals (OH) · ) and active chlorine substances can destroy the ultraviolet absorption (UVA) at 254 nm in landfill leachate. 254The organic materials are degraded to remove the bonds in the organic materials, thereby producing partially treated landfill leachate (PTLL). At least one second ultraviolet radiation source 26 is located in the second reaction chamber 14. A portion of the partially treated landfill leachate from the first reaction chamber 12 flows into the second reaction chamber 14, where it is then subjected to second ultraviolet radiation generated by the at least one second ultraviolet radiation source 26. Residual chlorine is removed through photolysis, thereby producing fully treated landfill leachate. It should be understood that... Figure 1 The overall configuration of the system 10 shown for electrochemical cyclic oxidation of landfill leachate is for illustrative purposes only and is not intended to be limiting.

[0022] exist Figure 1 Eight ultraviolet bulbs 24 are shown in the figure; however, it should be understood that this is for illustrative purposes only and any suitable type and any suitable number of ultraviolet radiation sources can be used.

[0023] exist Figure 1 The image shows six ultraviolet bulbs 26; however, it should be understood that this is for illustrative purposes only, and any suitable type and any suitable number of ultraviolet radiation sources can be used.

[0024] exist Figure 1 In this illustration, the positions, relative dimensions, and shapes of the first reaction chamber 12 and the second reaction chamber 14 are for illustrative purposes only. In this invention, their positions, relative dimensions, and shapes can be varied as long as their intended use is achieved. As a further non-limiting alternative, the first and second reaction chambers may be spatially separated from each other, or housed within the same integral housing, or located in separate, independent housings or units. In some embodiments, the first and second reaction chambers are located within an integral housing. In some embodiments, the first and second reaction chambers are located in separate housings.

[0025] In some embodiments, the system for electrochemically circulating and oxidizing landfill leachate further includes a one-way connecting conduit configured to unidirectionally connect a first reaction chamber and a second reaction chamber, thereby unidirectionally conveying the landfill leachate in the first reaction chamber to the second reaction chamber. Preferably, the one-way connecting conduit is a one-way pipe. Figure 1 The diagram shows a one-way conduit 28 for unidirectionally transporting partially treated landfill leachate from the first reaction chamber 12 to the second reaction chamber 14. It should be understood that any suitable type of conduit or other hardware or mechanism may be provided for transferring partially treated landfill leachate from the first reaction chamber to the second reaction chamber.

[0026] In some embodiments, the first and second reaction chambers also independently include stirring devices, such as mixers, agitators, or agitators, for continuously mixing and agitating the landfill leachate during treatment. Figure 1 As shown, one or more magnetic stirrers 30, 31 may be provided in the first reaction chamber 12 and the second reaction chamber 14, respectively. However, it should be understood that the magnetic stirrers 30, 31 are for illustrative purposes only, and any suitable type of mixer, stirrer, agitator, etc., may be used. As a non-limiting example, the magnetic stirrer may be replaced with an impeller suitable for continuous mixing in large-scale systems, or an impeller suitable for continuous mixing in large-scale systems may be added.

[0027] In some implementations, the system further includes a timer valve for controlling the discharge of fully treated landfill leachate from the second reaction chamber. Figure 1 The discharge of fully treated landfill leachate is controlled by timer valve 32.

[0028] In some embodiments, the anode comprises a metal oxide. In a preferred embodiment, the metal oxide is selected from the group consisting of IrO2, RuO2, and Ta2O5. It should be understood that other anode materials known in the art that can be used in the electrochemical oxidation process of the present invention may also be used, and the present invention does not further limit this.

[0029] In some embodiments, the cathode can be formed of any electrode material suitable for electrochemical oxidation of landfill leachate, and the present invention does not impose further limitations thereon. In a preferred embodiment, the electrode material of the cathode is titanium.

[0030] In some embodiments, the anode and cathode are powered by a DC power supply. It should be understood that other power supplies can also be used to connect to the anode and cathode, as long as the electrochemical oxidation reaction of the cathode and anode can occur, and the present invention does not impose further limitations on this.

[0031] According to a second aspect of the present invention, a method for electrochemically circulating oxidation of landfill leachate using the system described in the first aspect of the present invention is provided, comprising the following steps: (1) introducing landfill leachate into a first reaction chamber and electrochemically oxidizing the landfill leachate; (2) subjecting the electrochemically oxidized landfill leachate to first ultraviolet radiation using a first ultraviolet radiation source to generate partially treated landfill leachate; (3) conveying a portion of the partially treated landfill leachate to a second reaction chamber and subjecting it to second ultraviolet radiation using a second ultraviolet radiation source in the second reaction chamber to generate fully treated landfill leachate; and (4) discharging the fully treated landfill leachate from the second reaction chamber.

[0032] In some implementations, landfill leachate is introduced into the first reaction chamber for electrochemical oxidation to produce hypochlorite (OCl). - After a period of time following the initiation of electrochemical oxidation of landfill leachate, the treatment of landfill leachate and hypochlorite (OCl) was initiated. - The first ultraviolet radiation produces hydroxyl radicals (OH). · ) and reactive chlorine substances (RCS). Hypochlorite (OCl) - ), hydroxyl radicals (OH) · ) and active chlorine substances can destroy the ultraviolet absorption (UVA) at 254 nm in landfill leachate. 254 The organic materials are degraded to remove the bonds in the organic materials, thereby producing partially treated landfill leachate (PTLL). A portion of the partially treated landfill leachate in the first reaction chamber flows into a second reaction chamber, where it is then subjected to second ultraviolet radiation generated by at least one second ultraviolet radiation source. Residual chlorine is removed through photolysis, resulting in fully treated landfill leachate. In this invention, the combination of electrochemical oxidation and first ultraviolet radiation enhances the UVA of the landfill leachate. 254 The UVA levels in the treated landfill leachate were reduced by approximately 80%. The photolytic effect of the second ultraviolet radiation further reduced the UVA levels in some of the treated landfill leachate. 254 It decreased by 15-20%.

[0033] In some embodiments, in the initial stage (when the landfill leachate is entirely fresh), the combination of electrochemical oxidation and initial ultraviolet radiation is carried out for approximately 50-70 minutes, for example, 50, 55, 60, 65, or 70 minutes. In a preferred embodiment, the combination of electrochemical oxidation and initial ultraviolet radiation is carried out for approximately 60 minutes.

[0034] In some implementations, the current density of electrochemical oxidation is 100 A / m.2 Up to 300A / m 2 .

[0035] In some implementations, the first ultraviolet radiation dose is 5 mW / cm². 2 Up to 40mW / cm 2

[0036] In some implementations, the first ultraviolet radiation is applied to the landfill leachate 5 to 20 minutes after the start of electrochemical oxidation, that is, the application of the first ultraviolet radiation is delayed by 5 to 20 minutes after the start of electrochemical oxidation.

[0037] In some implementations, a portion, for example 5% to 50% (by volume), of the landfill leachate partially treated from the first reaction chamber is transferred to the second reaction chamber for subsequent dechlorination treatment.

[0038] In some implementations, the second ultraviolet radiation was administered for 5 to 10 minutes, for example, 5, 6, 7, 8, 9, or 10 minutes.

[0039] In some implementations, the ultraviolet radiation dose of the second ultraviolet radiation is 5 mW / cm². 2 Up to 40mW / cm 2 .

[0040] In some embodiments, fresh landfill leachate is conveyed to the first reaction chamber after a portion of the partially treated landfill leachate flows into the second reaction chamber. In a preferred embodiment, the volume of the fresh landfill leachate is equal to the volume of a portion of the partially treated landfill leachate conveyed to the second reaction chamber. After the fresh landfill leachate is conveyed to the first reaction chamber, where it is mixed with the partially treated landfill leachate already contained therein, the method of electrochemically cycling and oxidizing the landfill leachate can be restarted.

[0041] In some implementations, during the circulation phase in the first reaction chamber (i.e., mixing fresh landfill leachate with the remaining partially treated landfill leachate), the combination of electrochemical oxidation and first ultraviolet radiation is run for 10 to 15 minutes, for example, 10, 11, 12, 13, 14, 15, to reduce chlorine contact time and thus reduce toxic byproducts in the landfill leachate.

[0042] Figure 2 The dot plot shows the change in UV absorption at 254 nm in landfill leachate over time during the initial and recycling phases. Figure 2 As shown, in the initial stage, UVA 254 The amount is from 9cm-1 up to 15cm -1 During the initial 60-minute processing phase, UVA 254 The amount was reduced by approximately 80%. Because the recycling phase is carried out in the first reaction chamber using a mixture of fresh landfill leachate and the remaining partially treated landfill leachate, as expected, UVA... 254 The amount at the beginning is greater than the UVA at the end of the initial phase. 254 The amount was high, but it dropped rapidly within a limited time of about 15 minutes.

[0043] Figure 3 The dot plot shows the change in residual chlorine concentration over time during the initial and cycling phases. This is because the goal is to produce hypochlorite (OCl). - ), hydroxyl radicals (OH) · As described above, and with the presence of active chlorine substances, the residual chlorine concentration in the initial stage (first reaction chamber) starts from zero and steadily increases throughout the 60 minutes, as expected. The second reaction chamber reduces the residual chlorine to below 25 mg / L (Cl2) after each continuous cycle. According to practice in Hong Kong, in 3.5% v / v co-treatment of wastewater, the residual chlorine entering the wastewater pipe is below 1 mg / L (Cl2).

[0044] Figure 4 The bar chart shows the concentrations of chlorinated byproducts released after electrochemical cyclic oxidation of landfill leachate, specifically the concentrations of trichloromethane (TCM), trichloroacetaldehyde hydrate (CH), dichloroacetone (DCP), trichloroacetone (TCP), dichloroacetonitrile (DCAN), and trichloronitromethane (TCNM) after treatment and dilution to wastewater co-treatment at 3.5% v / v. For TCM, the World Health Organization (WHO) upper limit is 200 μg / m³. 3 The predicted ineffective concentration (PNEC) is 146 μg / m³. 3 .like Figure 4 As shown, the TCM concentration produced by the electrochemical cyclic oxidation method of landfill leachate is far lower than these two values, which clearly indicates that the electrochemical cyclic oxidation method of landfill leachate can be used safely.

[0045] In summary, the electrochemical cyclic oxidation method provided by this invention first electrochemically oxidizes landfill leachate to produce hypochlorite (OCl-), then delays the application of ultraviolet radiation to generate hydroxyl radicals (OH-) and active chlorine substances, breaking bonds in organic materials. Next, a portion of the partially treated landfill leachate is subjected to ultraviolet radiation for subsequent dechlorination through photolysis. Finally, the fully treated landfill leachate is discharged, and fresh landfill leachate is added to initiate the cycle, followed by another round of electrochemical oxidation and ultraviolet radiation. This allows for continuous treatment of landfill leachate. The electrochemical cyclic oxidation method provided by this invention enhances the UVA activity of landfill leachate. 254 Reduced by more than 80%, bringing the energy requirement for treating landfill leachate below 20 kWh / m³. 3 It significantly reduces energy expenditure, lowers the residual chlorine in fully treated landfill leachate to below 25 mg / L (Cl2), and the released chlorinated byproducts meet the standards and can be used safely.

[0046] It should be understood that the systems and methods for electrochemically cyclically oxidizing landfill leachate are not limited to the specific embodiments described above, but include any and all embodiments within the general language scope of the claims enabled by the embodiments described herein, or otherwise shown in the drawings or described in terms sufficient to enable a person of ordinary skill in the art to make and use the claimed subject matter.

Claims

1. A method for electrochemically cyclically oxidizing a landfill leachate, characterized in that, The method comprises the following steps: (1) introducing landfill leachate into a first reaction chamber to electrochemically oxidize the landfill leachate; (2) after 5 to 20 minutes of electrochemical oxidation, applying first ultraviolet radiation to the landfill leachate treated by electrochemical oxidation by using a first ultraviolet radiation source to produce partially treated landfill leachate; (3) conveying a part of the partially treated landfill leachate to a second reaction chamber, applying second ultraviolet radiation to the partially treated landfill leachate in the second reaction chamber by using a second ultraviolet radiation source to produce fully treated landfill leachate; and (4) discharging the fully treated landfill leachate from the second reaction chamber; wherein the method further comprises, after the step (4), conveying fresh landfill leachate to the first reaction chamber, the volume of the fresh landfill leachate being equal to the volume of the part of the partially treated landfill leachate conveyed to the second reaction chamber; wherein the part of the partially treated landfill leachate unidirectionally conveyed to the second reaction chamber is 5%-50% of the partially treated landfill leachate by volume.

2. The method of claim 1, wherein, The method is performed by using a system for electrochemically cyclically oxidizing landfill leachate, wherein the system comprises: a housing divided into a first reaction chamber and a second reaction chamber, wherein the first reaction chamber is unidirectionally communicated with the second reaction chamber, and wherein the housing has an inlet configured for inputting landfill leachate to be treated into the first reaction chamber and an outlet configured for discharging fully treated landfill leachate from the second reaction chamber; an anode and a cathode located in the first reaction chamber and configured for electrochemically oxidizing the landfill leachate inputted into the first reaction chamber; at least one first ultraviolet radiation source located in the first reaction chamber and configured for applying first ultraviolet radiation to the landfill leachate treated by the electrochemical oxidation after 5 to 20 minutes of electrochemical oxidation; at least one second ultraviolet radiation source located in the second reaction chamber and configured for applying second ultraviolet radiation to the landfill leachate from the first reaction chamber; and a unidirectional communication pipeline configured for unidirectionally communicating the first reaction chamber with the second reaction chamber so as to unidirectionally convey a part of the partially treated landfill leachate in the first reaction chamber to the second reaction chamber; wherein the system, after discharging fully treated landfill leachate from the second reaction chamber, conveys fresh landfill leachate to the first reaction chamber, the volume of the fresh landfill leachate being equal to the volume of the part of the partially treated landfill leachate conveyed to the second reaction chamber; the cyclic stage of the system makes the combination of electrochemical oxidation and first ultraviolet radiation run for 10 to 15 minutes.

3. The method of claim 2, wherein, The first reaction chamber and the second reaction chamber are located in one integral housing.

4. The method of claim 2, wherein, The first and second reaction chambers are each located within a separate housing.

5. The method of claim 2, wherein, The one-way communication conduit is a one-way duct.

6. The method of claim 2, wherein, The first and second reaction chambers each independently further comprise a stirring device.

7. The method of claim 6, wherein, The stirring device is a mixer, a stirrer, a blender.

8. The method of claim 2, wherein, The anode comprises a metal oxide.

9. The method of claim 8, wherein, The metal oxide is selected from the group consisting of IrO2, RuO2, and Ta2O5.

10. The method of claim 2, wherein, The anode and cathode are powered by a direct current power source.

11. The method of claim 1 or 2, wherein, The method further comprises restarting electrochemical cyclic oxidation of landfill leachate after delivery of fresh landfill leachate to the first reaction chamber.

12. The method of claim 1 or 2, wherein, The current density of the electrochemical oxidation is 100 A / m 2 up to 300 A / m 2 .

13. The method of claim 1 or 2, wherein, the first ultraviolet radiation and the second ultraviolet radiation each independently is from 5 mW / cm 2 to 40 mW / cm 2 .

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